1. Field of the Invention
This invention relates to a continuous path enlarger and in particular to an illumination system therefor. 2. Description of the Prior Art
The problem solved by the present invention is that of illuminating a very wide object (such as 17 inches wide) sufficiently to properly expose a much wider (such as 84 inches wide) light sensitive recording sheet in as short a time as possible with both the original and recording sheet moving synchronously with each other. The problem is complicated in the present instance by the fact that the recording material is preferably a diazo material that is relatively insenstive to light and also by the fact that its sensitivity is in the ultra violet region where it is difficult to get a large percentage of illumination or irradiance at the image plane since optical systems themselves absorb a considerable amount of ultra violet. The original moves past a large slit about 17 inches long and about 2 inches wide. Normally optical systems are rotationally symmetrical, so that a straight-forward solution to the problem would be a circular condenser lens 17 inches in diameter, however, to do this most of the light would be lost, plus the lenses would be extremely expensive since the cost thereof is proportional approximately to the cube of the diameter, and also the manufacture of the machine itself would be very complicated because the allowed tolerances would be very small because of the aperture and depth of the focus of a large aperture projection lens.
It is therefore an object of the present invention to provide an illumination system that solves the above-mentioned problems and in particular by providing a plurality of illumination sources each including a light source and a lens system, with the lens systems having a final element with straight edges at an angle to the direction of travel of the recording material. It is another object of the invention to provide such an illumination system wherein the individual image areas on the recording sheet overlap one another.